The present invention relates to a high-compound function acrylic synthetic fiber, which has three functions such as deodorizing performance, antibacterial/bacteriostatic performance and water absorption/sweat absorption performance and is also superior in washing durability, and a method of producing the same and a nonwoven fabric.
Acrylic synthetic fibers have widely been used in clothes, bedding, upholstery and the like. In these uses, deodorizing performance, antibacterial/bacteriostatic performance and water absorption/sweat absorption performance are indispensable to a comfort and healthy life style. Although products having a compound function obtained by fiber mixing, mixed spinning, union cloth or union knit of deodorizing fibers, antibacterial/bacteriostatic fibers and water absorption/sweat fibers and products having a compound function obtained by applying a post-processing system to a single function material have hitherto been marketed, these products require special facilities and production technologies and are uneconomical due to high cost.
Japanese Unexamined Patent Publication (Kokai) No 9-87924 and Japanese Unexamined Patent Publication (Kokai) No 9-157978 disclose an acrylic synthetic fiber having both antibacterial and deodorizing performances and a fiber product containing the same. Although these publications relate to an acrylic synthetic fiber containing a silicic acid metal salt or an aluminosilicic acid metal salt, fiber products described in these publications had poor water absorption/sweat absorption performances.
The present invention have made a trial of improving the technologies described above and found that an acrylic synthetic fiber comprising a fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt having a specific apparent specific gravity as an active component has antibacterial/bacteriostatic performance and deodorizing performance superior, which are superior to the prior art, and is also superior in water absorption/sweat absorption performance, thereby leading to the completion of the present invention.
An object of the present invention is to provide a high-compound function acrylic synthetic fiber, which has three functions required strongly by consumers, for example, deodorizing performance, antibacterial/bacteriostatic performance and water absorption/sweat absorption performance, and is also superior in washing durability, a method of producing the same and a nonwoven fabric, for the purpose of aiming at a high quality life and providing a safe/sanitary, healthy and comfort life style.
The gist of the present invention is an acrylic synthetic fiber comprising 0.5 to 20.0% by weight of a fine powder, which contains a silicic acid metal salt or aluminosilicic acid metal salt having an apparent specific gravity of 0.5 g/cm3 or less and an average particle diameter of 0.5 to 10 xcexcm as an active component.
Also, it is a method of producing an acrylic synthetic fiber, which comprises uniformly dispersing 10 to 40% by weight of a fine powder, which contains a silicic acid metal salt or aluminosilicic acid metal salt having an apparent specific gravity of 0.5 g/cm3 or less and an average particle diameter of 0.5 to 10 xcexcm as an active component, in a solvent; adding the dispersion to a dope of a copolymer containing acrylonitrile; and spinning the mixed solution.
Furthermore, it is a nonwoven fabric comprising at least 10% by weight or more of the acrylic synthetic fiber of an acrylic synthetic fiber comprising 0.5 to 20.0% by weight of a fine powder, which contains a silicic acid metal salt or aluminosilicic acid metal salt having an apparent specific gravity of 0.5 g/cm3 or less and an average particle diameter of 0.5 to 10 xcexcm as an active component.
The present invention will now be described in detail.
The acrylic synthetic fiber used in the present invention is made of an acrylonitrile copolymer containing at least 40% by weight of acrylonitrile, and any copolymerizable monomer can be used in combination with the acrylonitrile. Examples thereof include those which are obtained by copolymerizing an appropriate combination of a neutral monomer such as acrylic acid alkyl ester (e.g. methyl acrylate, ethyl acrylate, etc.), methacrylic acid alkyl ester (e.g. methyl methacrylate, ethyl methacrylate, etc.), styrene, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl ethyl ether, or methacrylonitrile, an acid monomer such as acrylic acid, methacrylic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, or 2-acrylamide-2-methylpropanesulfonic acid, and an ammonium salt or an alkali metal salt of these monomers in the proportion of 60% by weight or less. These acrylic copolymers may be prepared by any method such as suspension polymerization method, solution polymerization method, emulsion polymerization or the like.
The fine powder used in the present invention contains, as an active component, a silicic acid metal salt or aluminosilicic acid metal salt having a three-component composition of 5-70% by weight of SiO2, 5-80% by weight of MOn/2 and 1-35% by weight of Al2O3 in terms of oxide (M represents at least one metal selected from zinc, copper, silver, cobalt, nickel, iron, titanium, barium, tin, magnesium or zirconium, and n represents a valence of metal).
It is considered that such a metal salt has both properties of a solid acid and a solid base in a crystal thereof and also independently exists on the surface of one solid particle to form an amphoteric adsorption face without neutralizing with each other and, therefore, it exerts excellent deodorizing effect on a basic malodorous substance and an acidic malodorous substance by means of a chemical adsorption action. It is also considered that the metal salt is superior in contact efficiency with the malodorous substance because of large specific surface area and small apparent specific gravity, and also has a physical adsorption action, thereby making it possible to effectively deodorize. It is considered that the antibacterial/bacteriostatic performance originates in metal ions retained on at least a portion of fine powders, though the mechanism thereof is not sure.
The apparent specific gravity of the fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component used in the present invention is 0.5 g/cm3 or less, and preferably from 0.5 to 0.2 g/cm3. The apparent specific gravity of the fine powder is important to the water absorption performance and deodorizing performance. When the apparent specific gravity exceeds 0.5 g/cm3, the water absorption performance and the deodorizing performance are drastically lowered. In the present invention, the water absorption performance as well as extremely excellent deodorizing performance and bacteriostatic performance are obtained by incorporating a fine powder having (very) small apparent specific gravity into an acrylic synthetic fiber. The fine powder having (very) small apparent specific gravity attains the water absorption performance from voids formed in the vicinity of the fine powder in the fiber. Furthermore, the contact efficiency with the malodorous substance and the bacteria medium could be improved and a rapid improvement in deodorizing performance and antibacterial/bacteriostatic performance could also be achieved.
It is necessary that the average particle diameter of the fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component used in the present invention is from 0.5 to 10 xcexcm. When the average particle diameter of the fine powder is less than 0.5 xcexcm, agglomeration is liable to occur and it becomes difficult to uniformly disperse the fine powder unless a special dispersing device or a dispersant is not used. On the other hand, when the average particle diameter of the fine powder exceeds 10 xcexcm, an increase in filtration pressure and fiber breakage occur during spinning and, therefore, it is not preferred in view of the operability. In view of the dispersion stability of the dispersion of the fine powder and the spinning operation stability, the average particle diameter is more preferably from 1 to 6 xcexcm. Although the particle size distribution of the fine powder is not specifically limited, the fine powder having a more narrow particle size distribution is preferred, as a matter of course, in view of the quality stability and production stability.
The specific surface area of the fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component used in the present invention is preferably 100 m2/g or more, and particularly preferably 150 m2/g or more, in terms of a BET specific surface area. When the BET specific surface area is less than 100 m2/g, the contact efficiency between the fine powder and the malodorous substance is lowered and, therefore, sufficient deodorizing capacity can not be exerted.
The amount of the fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component used in the present invention is from 0.5 to 20.0% by weight, and preferably from 1.0 to 15.0% by weight, based on the acrylonitrile copolymer. When the content of the fine powder is less than 0.5% by weight, sufficient deodorizing performance, antibacterial/bacteriostatic performance and water absorption/sweat absorption performance can not be imparted. On the other hand, when the content exceeds 20.0% by weight, the fiber-formability, physical properties of the single fiber and spinnability are drastically lowered during the spinning and, therefore, it is not preferred.
As the solvent used in the present invention, any solvent may be used as far as it can dissolve the acrylonitrile copolymer. Examples thereof include organic solvents such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide, acetone and the like and these organic solvent in view of the solubility, recovery of the solvent, and handling.
To maintain the dispersion stability of the fine powder and to avoid sedimentation of the fine powder in case the fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component used in the present invention is dispersed with stirring, dispersants are preferably used in combination. The dispersant is not specifically limited, but an amphoteric surfactant and an anionic surfactant are more preferred as compared with a nonionic surfactant and a cationic surfactant when the solvent, in which the dispersant is dispersed, is a protic high-polar solvent.
In case of dispersing the fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component used in the present invention in a solvent solution, wetting characteristics come into question. Since the fine powder having small apparent specific gravity, large BET specific surface area and large average particle diameter exhibits poor wetting characteristics to the solvent solution, the surface of the fine powder to be dispersed is preferably hydrophilized. The hydrophilization method is not specifically limited but includes, for example, surface treatment with a hydrophilic surfactant, treatment for hydrophilization of the surface of a fine powder or the like.
In case of dispersing the fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component used in the present invention in the solvent, a physical grinding facility such as wet mill, sand grinder or the like is used in preferably used in view of the dispersion stability, prevention of sedimentation, spinning operation and quality stability. However, the fine powder of the present invention can be spun without using a special facility.
The method of incorporating the fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component into the acrylonitrile copolymer may be, for example, a method of adding a dispersion, which is prepared by dispersing a fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component in a solvent, to a spinning stock solution prepared by dissolving an acrylonitrile copolymer immediately before spinning, followed by mixing.
In the method of dispersing and dissolving the fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component used in the present invention in a solvent and the method of adding the resulting solution to a spinning stock solution containing an acrylonitrile copolymer, followed by mixing, the mixing operation can be sufficiently carried out by a conventional mixer.
In the present invention, the concentration of the fine powder containing a silicic acid metal salt or aluminosilicic acid metal salt as an active component to be dispersed in the dispersion is from 5 to 40% by weight, and preferably from 10 to 35% by weight. When the concentration is less than 5% by weight, the concentration of the acrylonitrile copolymer in the spinning stock solution is reduced and, therefore, the fiber-formability and physical properties of the fiber are lowered. On the other hand, when the concentration exceeds 40% by weight, good dispersion can not be obtained, thereby making it impossible to produce the fiber industrially easily.
As far as the characteristics of the present invention are not impaired, conventionally used functional modifiers such as titanium doxide, flame retardants, light proofing agent and heat accumulating agents may be further added.
The resulting spinning stock solution is spun through a conventional spinneret. All publicly known wet, dry-wet and dry spinning methods can be applied as the spinning method and the spinning may be carried out under the same conditions as those in case of a conventional acrylic synthetic fiber.
Although the spinning conditions are not specifically limited as far as a stable operation can be carried out under the conditions, the spinning entire draw ratio is preferably as high as possible so as to form voids in the vicinity of the fine powder contained in the fiber. For example, high draw ratio is preferably selected in the drawing step after drying and densifying in case of the wet spinning method. Although the drawing temperature conditions after drying and densifying are not specifically limited, the draw ratio is 1.2 time or more, and preferably 1.3 times or more. High draw ratio is preferred for deodorizing performance, antibacterial/bacteriostatic performance and water absorption/sweat absorption performance as far as physical properties of the single fiber are not drastically lowered and a stable operation can be carried out.
As far as the characteristics of the present invention are not impaired, surface modifiers such as coating may be used in combination with the silicic acid metal salt or aluminosilicic acid metal salt so as to improve the solvent dispersion stability and the wetting characteristics with the solvent.
To the fiber of the present invention, any uses, products and production methods, which can be realized in a general acrylic synthetic fiber, can be applied. In this case, other fibers (for example, natural fiber such as cotton fiber and synthetic fiber such as modacrylic fiber) may be mixed in the product of the present invention. The mixing method includes, for example, mixed spinning method, mixed weaving method, cross knitting method or the like.
The nonwoven fabric of the present invention will now be described. The nonwoven fabric of the present invention is a nonwoven fabric containing at least 10% by weight or more of the acrylic synthetic fiber described above. This nonwoven fabric can provide a functional nonwoven fabric while maintaining functional characteristics such as deodorizing performance, antibacterial/bacteriostatic performance and water absorption/sweat absorption performance of the above-described acrylic synthetic fiber according to the present invention.
It is necessary that the nonwoven fabric comprising at least 10% by weight or more of the acrylic synthetic fiber of an acrylic synthetic fiber comprising 0.5 to 20.0% by weight of a fine powder, which contains a silicic acid metal salt or aluminosilicic acid metal salt having an apparent specific gravity of 0.5 g/cm3 or less and an average particle diameter of 0.5 to 10 xcexcm as an active component. When the amount of the acrylic synthetic fiber is less than 10% by weight, the deodorizing performance and antibacterial/bacteriostatic performance of the nonwoven fabric are drastically lowered, thereby making it impossible to impart desired high level function.
To make the most of viewpoint of cost performance as well as functional characteristics of a mixing material as a merit of composite textile fabric and composite nonwoven fabric, the content of the acrylic synthetic fiber is as small as possible as far as high functions such as deodorizing performance and antibacterial/bacteriostatic performance of the acrylic synthetic fiber according to the present invention can be maintained. Preferred is a nonwoven fabric containing 10 to 50% by weight, and more preferably 10 to 35% by weight of the acrylic synthetic fiber of the present invention.
The mixing material may be either a natural finer or a chemical fiber and is not specifically limited as far as the nonwoven fabric contains 10% by weight or more of the fiber of the present invention. The mixing method may be any publicly known method. Any method may be used as far as the nonwoven fabric contains 10% by weight or more of the fiber, for example, single-layer nonwoven fabric using a material alone or in combination with the other material, and multi-layer nonwoven fabric.
In the production of the nonwoven fabric, any conventionally known method can be employed. Various single-layer and multi-layer nonwoven fabrics can be produced by using, for example, apparatuses for production of dip bond nonwoven fabric, heat fusing nonwoven fabric, needle punch nonwoven fabric, stitch bond nonwoven fabric, span bond nonwoven fabric, wet nonwoven fabric and the like.
Specific uses and products of the present invention include pile goods (e.g. bore sheet, blanket, etc.), cover/side texture goods (e.g. sheet, pillow case, futon cover, etc.), cotton wool pad goods (e.g. futon, kotatsu futon, Japanese cushion, bed pad, pillow, cushion, etc.), robe, throw blanket, bedspread, bathrobe, bath towel, body towel, etc. in the field of bedding. In the field of interiors, there can be exemplified toiletry goods (e.g. toilet seat cover, toilet lid cover, toilet mat, etc.), drapery goods (e.g. curtain, lace, casement, blind cloth, etc.), carper goods (e.g. entrance/bath/kitchen mat, rug, carpet, hot carpet, etc.), cover cloth goods for OA chair,upholstery, etc., lining for kotatsu futon, and table cloth.
In the field of clothes, there can be exemplified inner goods (e.g. underwear, tights, spats, leg warmer, etc.), outer goods (e.g. sweater, fleece, fake fur, inter liner for protection against the cold, etc.), socks goods (e.g. socks, etc.), room wears (e.g. apron, coverall apron, urinal stall, hood cape, pajama, etc.) and business uniforms (e.g. white robe, surgical clothes, etc.). In the field of materials, there can be exemplified footwears (e.g. slipper, animal shoes, shoes for protection against the cold, etc.), dust controlling goods (e.g. business mat, cleaning mop, etc.) and building materials for residence (e.g. wallpaper, etc.).
In the field of nonwoven fabrics, there can be exemplified nonwoven fabrics for residence and building materials (e.g. sheet for prevention of dew condensation, curing sheet, low partition, high partition, ceiling material, wallpaper, etc.), agricultural nonwoven fabrics, business/household wiping nonwoven fabrics (e.g. industrial wiper for food supply center such as catering and door-to-door parcel delivery service, wet towel, business dishcloth, flooring wiper, toilet tissue, wet tissue, paper towel, etc,), household sundry nonwoven fabrics (e.g. bag, sheet, wrapping cloth, packing material, cover for clothes, draining bag, etc.), filter nonwoven fabrics (e.g. building air-conditioning filter, automobile filter, household air cleaner filter, business air cleaner filter, mask, cleaner filter, etc.), nonwoven fabrics for use as automobile interior skin materials and secondary materials (e.g. needle punch carpet, ceiling material, wading members, etc.), medical nonwoven fabrics, for example, surgical nonwoven fabrics (e.g. gown, drape, mask, cap, sheet, towel, underpant with hole, underpant for patient, surgical underwear, sterilized packing material, shoes cover, delivery pack, gauze, etc.) and base nonwoven fabric for percutaneous drug such as cataplasm, plaster, etc., nonwoven fabrics for sanitary materials such as paper diaper member, sanitary napkin member, etc., disposal clothes used in medical care, nursing care, laboratory, food processing and food manufacturing, nonwoven fabrics for clothes (e.g. liner for clothes, sweat absorbing pad, bust pad, etc.), nonwoven fabrics for shoes members (e.g. shoes liner, insole, etc.). The products and uses are not specifically limited. Any publicly known production method may be used as the method of producing products and half finished products.